Here is a link to a good music theory site. If you want to learn some music theory (how scales and chords and built). I like this site especially the fact that they put up the key signature calculator.. Even if you don't want to know alot of theory  it will help .
http://www.musictheory.net/

sometime around Bach, the triad became the common chord, and it is constructed by playing two notes a third apart and then adding another note a third above the higher note. A third is a musical interval, on a guitar, notes three frets apart ( ie open E and third fret on E ) or notes that are four frets apart ( ie open E and fourth fret on E ). The two notes that are three frets apart are called a minor third, and the notes four frets apart are called a major third.These are the "Official" classical names for the intervals. A major chord has a major third first ( ie E and G# ) followed by a minor third ( ie G# and B). I can do a complete tutorial on chord theory later. This only covers basic root position chords and doesn't cover inversions. If any of this makes sense, or if none of it makes sense, PM me and I will be able to explain it another way.

PS
It is harder to learn chord theory on guitar. It is easier on piano. The basic guitar chords you know, are not always voiced normally...

anyways, contact me if you still need help...

There are some chord progressions that are very common. You see them mostly in Bach music and 50's ballads. In order to show a chord progression that can be transposed to any key, one must represent each degree of the scale with a roman numeral. The tonic will be rep resented with I, etc. and the seventh scale degree with vii*. What makes the numerals upper-case, lower-case, or lower case and *'ed is what type of chord is being used. Upper-case means Major chord. Lower-case means Minor chord. Lower-case and * means Diminished.
Typical chord progression
I -> vi -> ii or IV -> V or vii* -> I -> ...
In the key of C the progression is as follows. C-> Am -> Dm or F -> G or B dim -> C...
This progression already has options, but gets boring fast. Luckily, there is room for improvement within a chord progression to give yourself more options. For instance, depending on the other instruments parts, you can put any chord that sounds good between the C and Am. The only necessary part of any chord progression is an end. I mean lets be honest, to song has to end some time. The end of a chord progression us called a cadence. There are a few common cadences that most progressions end with. One is V -> I or G to C. Another is vii*-> I, or B dim to C. Another that is common in church hymns is IV -> I, or F to C.
But, some music written in the last 100 years has used different types of chord progressions that are ruled by, usually mathematical principles.

Hope that helped you formulate progressions faster!

Also, there are things called secondary dominants, which you can google, I'm just feeling lazy, and don't want to explain them now...