Ok, here goes. Learn to think of notes in terms of numbers. Chords are made up of cetain notes in a scale. For major chords, it is always the first note in the scale., which is called the root, the 3rd and 5th note of the scale. In the key of C for instance 1=C, 3=E and 5=G. All majors are 135. Write out the intervals in the Key of C. C,D,E,F,G,A,B,C. Write the numbers underneath them1,2,3,4,5,6,7,8. Now you can biuld chords if you know what numbers or intervals make up that Chord. Keep in mind that there are sharps or flats bewtween some of those notes. So compare the formula for the chords against the notes they line up with. minors 1,b3,5. A minor always has a flat third. A 7th is just adding the 7th note etc. There are a few more rules that go along with chord construction but, you get the idea. Here is a link to a chord finder that shows almost all the chords you will ever need using the intervals or numbers for the note positions.
http://www.looknohands.com/chordhous.../index_rb.html
chord house ::: guitar room (advanced) -- online guitar chords and scales
You will see that at that site that playing a C minor as an open chord at the nut is a tough one. Doing a bar chord is a lot easier. A capo , of which there are many styles, presses down on the strings behind the fret of your choice to change the key your playing in. If you cappoed at the 3rd fret, you would be playing in the key of G for instance. You could probably google for answers to some of your questions or buy a simple music book. There is usually someone hanging around here to answer questions so just ask. Good luck