If there are curved seals, fit these to the engine. Smear sealant on the seal groove, stick the seal in place, and apply a blob of sealant to each end of the seal where it joins the gasket.
(6) Note that there should be a certain amount of lubricating oil on the lip of the oil seal.
Scrape off all the traces of dirt and old gasket from the engine and sump flanges with a paint scraper.