I don't really know many sites- I forget to bookmark stuff- but here are some basic things to help get you started:
If you are playing a standard 4-string, the line below the bass clef is your lowest note- the open "E" string.
Your open "A" string is the bottom space in the bass clef, as is the 5th fret on your E string.
Your open "D" string is the third line from the bottom of the bass clef, or the middle line of the clef, as is the 5th fret on your A string.
Your open "G" string is the top or fourth space from the bottom of the bass clef, as is the 5th fret on the A string.
When comparing notes to frets, remember that each note skips a fret, except for when you go E-F or B-C. For example- if you are on the "A" string, the placement would be like this:
A= Open string
Bb(B flat) OR A# (A sharp)= 1st fret
B(Cb)= 2nd fret
C(B#)=3rd fret
Db or C#= 4th fret
D=5th fret
Note- B# and Cb are the SAME NOTE, as are E# and Fb, they are just written differently. You will learn why further down the road.
The bass clef notes look like this on paper:
----Middle C--- (1string, 5th fret)
B (1st string, 4th fret)
|----A--------| (1st string, 2nd fret)
| G | (1st string OR 2nd string 5th fret)
|----F--------| (2nd string, 3rd fret)
| E | (2nd string, 2nd fret)
|----D--------| (2nd string OR 3rd strign 5th fret)
| C | (3rd string, 3rd fret)
|----B--------| (3rd string, 2nd fret)
| A | (3rd string OR 4th string 5th fret)
|----G--------| (4th string, 3rd fret)
F (4th string, 1st fret)
---E---- (4th string)
To play a sharp (#) of any of these notes, go up one fret.
To play a flat (b) of any note, go down one fret.
I hope this helps you out a bit and didn't confuse you
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Notes 
