Draw a line AB. Take a point P outside it. Draw a line passing through P and parallel to AB.
1.Draw a line AB.
2. Take any point S on AB and a point P outside AB and join PS.
3. With S as center and any radius draw an arc to cut AB at M and PS at N.
4. With P as center and same radius draw an arc to cut PS at F.
5. With as center and radius equal to MN, draw an arc to cut the previous arc at E.
6. Join PE and produce it on both sides to get the required line CD parallel to AB.