Open your chord book to the table of contents and find the pages that teach the chords "C", "F", "G" and "A minor."
Practice playing the chords in one of the following orders:
Am, F, C, G, (repeat)
C, G, F, C
C, F, C, G, C
Use your favorite search engine online to search "Worship chords". You may also search for the name of your desired Christian song. (See Resources.)
Print out these chords and practice singing while playing. It will get easier the more you do it.