To play the E note, pick the open 6th string.
Play the F note with the first finger of your left hand behind the first fret of the 6th string.
Play the G note with the third finger of your left hand behind the third fret of the 6th string.
Here is a summary of all the notes you have learnt so far.
The example below uses these three new notes along with all the other notes you have learnt. Notice that the notes on the sixth string are lower versions of the notes on the first string and require extensive use of leger lines in the written music.