Fix the seal first
While the cover is off clean out any emulsified oil you can access and re-fit the cover with a new gasket...wemoto?
Fill to the required level with diesel (red if you can get it...its cheaper), start the engine and allow it to warm up..and the drain the diesel remembering to lean the bike to the right to drain effectively...dispose of diesel and drained oil properly at your local refuse site
Fill to correct level using motorcle specific oil