I'm not sure what this is for.

I'm not sure what this board is for. Still, I do have a question about the following sentences. Is it awkward if you say that someone 'wears simple clothes,' or that 'he dresses simply'? Also, for the next expression, 'help me ~ing', which would be more commonly used? Are both sentences correct in grammar? 1. Please help me in making this report. 2. Please help me with making this report.

I apologize it has taken me so long to reply.

The clause "He wears simple clothes" is gramatically fine, as is "He dresses simply".

Regarding your next question, both are correct but you are much more likely to hear "Help me make this report" than either 1 or 2.  We Americans don't use 5 words when 3 will suffice!

I hope this has helped.

-Michael