Just go to any fabric store, ask for the pattern section & you'll see everything from socks to jean jackets etc., in your size even. Also pick up some leather needles, either hand or machine ones if you access to a good sewing machine.
Cut out the lining fabric (for a jacket say) as per pattern, pin or stable it together & rough fit it. Then proceed with cutting the leather & pinning or stabling & rough fit.
When adjusted, sew 'er up keeping all your stitching straight or on line for curves etc. Lining first, etc. Most patterns have some instructions, or any simple sewing book from the library will have all you need to know.
I use contact cement for leather to leather hems etc. Don't forget to remove pins & stables BTW.
Nothing to it! Good luck! - Q.