You can first read about the basic circuits and how to build them using standard CMOS circuits. "Digital Integrated Circuits : a design perspective" by Rabaey covers this part in a very good and illustrative way. You'd usually need NANDs, ANDs, ORs, NORs with different number of inputs ,NOT ,MUXs, Half adders ,full adders ,latches, registers ,XORs ,XNORs.
After finishing the circuits, start performing the layout. Each cell should have a Vdd rail at its top and a ground rail at its bottom. All cells should have constant height to ease assembling them at higher level blocks. Try to minimize the use of higher metals and use poly extensively (if delay is not an issue) to save higher metal for higher level routing.Also, try using same N-well for all PMOSs for same cell. Pass DRC and LVS for each cell.
Good luck as this usually takes time.