Hi Mary
When making curtains in plain fabrics I always press in the hems and top fold in for each width before joining the fabrics together. Cut your drops and allow them to rest for at least 24 hours.
Fabrics should be allowed to recover after being taken off the roll, this is done by resting the drops when cut and be aware, they will shrink up a little! Once rested lay them flat on the table, line the side of the fabric with the edge of the table to get your square, fold and press the hem in using the corner of the table as a guide. Measure up from the bottom to get your length and fold and press the top. Do this to all drops and then sew together.
make sure your fabrics lengths are laying flat before pressing inWith regards to laying the lining in: If you use a double 3" hem on the curtain fabric and a double 2" hem on the linings you will be able to line the lining up with the hem easier. Lay the curtain fabric out on the table, lay the lining on and interlock the first width and sew in the sides, pin the tops to hold in place.. It's a case of folding as you go through the widths now. Any creases will drop out once hanging.
Hope this helps!
Philip
Decozo