The following example contains the G and D7 chords. When changing from G to D7, do not lift your third finger off the string, but slide it down to the second fret.
Only touch the string very lightly as you do this.
When changing from D7 to G, slide your third finger up to the third fret.
Here are some songs to practice your chord changes with.
These melodies contain all the notes you have learned so far.
Fingerpicking is mostly played on acoustic guitars. If you are playing in public, at some point you will need to amplify your guitar.
The most common way of doing this is to get a pickup fitted to your guitar and plug it into either an acoustic guitar amp, or the PA system used by the singer. There are many pickups available for acoustic guitars and most can be attached for a performance and then removed until required again.