Below are videos taken from YouTube that will help with your playing

This video shows how to make the best embrochure (mouth shape) for getting good sound from a baritone or trombone

here is more on embrochure, plus tounging and the first 3 notes; d, c, and b-flat;

WATCH THIS....it is about your air stream, which makes for good tone

more on getting good sound;

here are some tips on producing good, clear tone;

and here is a great overview of the basics;

here is a reference for reading the lines and spaces on the bass clef;

notice that I said 'reading lines and spaces"  NOT  "reading notes.

this is because it is the lines and spaces that are named : A,B,C,D,E,F,and G. The notes themselves are actually named only for the amount of time they are held for :
quarter note = 1 beat
half note = 2 beats
whole note = 4 beats
and so on. 
IF YOU SAW THE HEAD OF SQUIDWARD ON THE BOTTOM LINE OF THE TREBLE STAFF, YOU WOULD PLAY AN   'E'. I don't know how LONG you would hold it for, but it would be played as  'E' because ANY note symbol on the bottom line of the staff is played as   'E'