MsWills
First of all, have a look at our ESA Claim guides.
www.benefitsandwork.co.uk/help-for-claimants/esa1 If your ME is moderate then it is likely to be quite variable you need to explain this on the ESA50 giving details of how you are at your worst and how you are the majority of the time, in both cases, you need to explain how long you are affected in each way. You need to do this for each of the activities that you hope to score points for.
If you have specific questions then please reply to this post and we will do our best to help.
Gordon