If you don't know how to use tablature to read music don't feel bad. everyone starts somewhere. There are plenty of websites with tablature and they tend to assume everyone understands how it works. I once had a bass student who didn't know how to read traditional music notation and thought the lines of the staff represented the strings, although he had a standard 4 string bass, and there are 5 lines in a staff. I thought that was a pretty interesting guess, and explained there was a system like that, but the staff, with a clef at the start, letting you know if it's bass or treble, was not it.
Tablature is a system of music notation, that is to say, a way of writing it down so you can read it, even if you can't read music in the traditional way, little black dots with stems and flags on a staff. In essence, tablature is a graphic representation of the actual strings of an instrument, like a bass, or a lesser instrument like guitar, here is a sample of bass tablature:
G--------------------------------------------|
D--------------------------------------------|
A--------------------------------------------|
E--------------------------------------------|
The dashed lines are actually a picture of your strings, in this case on a four string bass. The letters are the names of the strings, (you can't completely escape music theory). The thinnest string is G, and the fattest string is E, unless your bass is left-handed. So if you put it down on your lap and look down at the neck, you can visualise the tablature as a picture of the strings.
This sample actually has some notes on it.
G--------------2-4-5-------------------------|
D-------2-3-5--------------------------------|
A--3-5---------------------------------------|
E---------------------------------------------|
Here the numbers tell you which fret to play, count the open string as zero, the 3rd fret will often have a black dot set into it, the 5th one will almost always have a fret marker for reference, as does the 7th, 9th, and the 12th will have 2 dots usually, or rectangular fret markers. Dots usually appear on the top side of the neck, where you can see them if you're standing up, or playing with a strap on and the neck is not flat with the strings facing up.
So you read the tablature above as follows, play the 3rd fret on the A string, then the 5th fret, the numbers are moving forward in time, as they move to the right. after the 5th fret on the A string, you can see the next number indicated is a 2, so you play the note on the 2nd fret, but it's on the D string, and keep going up from there. If you follow that tab correctly and your instrument is in tune, you should hear a C major scale.
Other forms of tablature may have different numbers of strings represented, Tab for 5 string bass, or 6 string bass, or guitar. Alternate tunings may also be indicated with differing letters on the left, the notes accompanying the tablature will probably mention to look out for things like that though.
As I thought, just looking at some tab sites, most of them assume you understand it, that's why I made this page. I did come across this useful tutorial as well which has basically the information I outlined above, plus a few notes about other annotations, such as bends, and slides. http://www.studybass.com/lessons/reading-music/how-to-read-bass-tab/
As that site points out, tablature often gives no clue about rhythm, expecting you to pick that up by ear. I do suggest learning to read music notation as it will open up a world of music to you which you may not be able to find in any other form, as well as allowing you to write down your own music, including the rhythms, so you can publish it, share it with bandmates or students of your own, or just impress your friends. On the internet it's harder to find traditional music notation, or sheet music, generally searches for it will result in mostly pages offering to sell you books of it. If you go into a music store, a good one will have books of music, libraries also carry them, good books will have the music written several ways, little grid pictures of chord charts for guitarists, the staff with music notation on it, and also tablature. Professionally published music has a greater chance of being accurate, than transcriptions you will find online, although you still have to use your ears to make sure what is written, no matter by whom, is what was played. Often the books are written for pianists, and the basslines are only approximate, unless it specifies otherwise. Some books are up front about it, like "Easy guitar Beatles songs" which don't have accurate chord voicings, but will get a beginner rolling, and having fun.
I had a teacher at Berklee who told us about a friend of his who transcribed music professionally for publication, he'd receive a vinyl LP and have to write down the music on it so they could make a book (back in the 80's). The belt on his turntable was starting to go, however, that's a big rubber band essentially, and the speed of the records was off, and consequently the pitch, so he actually transcribed a song which was originally in the key of C, as being in the key of C# (C sharp), which involved a lot more ink, as every single note was now sharp, which was just absurd, and it got published before he realised he needed to replace his turntable belt. No names were mentioned, and to protect thhose involved I won't disclose the teacher's name.