I don;t know music theory, but I want to make a little lead part for a song. How would I do this?

Say this is my riff
Tuned to D


|-----------------------------------|
|-----------------------------------|
|-----------------------------------|
|---5-2-4-2-5-3---------------------------|
|---5-2-4-2-5-3---------------------------|
|---3-0-2-0-3-1----------------------------|

And this keeps repeating

Do I have to use the notes in these chords for the lead?