I noticed there are a lot of questions about positions and what key to use. The following url is a great piece of information for new and experienced.
One of the best things I found is the Layout Generator. It tells you what notes can be played and where they are hiding on any key harmonica. Tell it the key and what position you wish to play and “BAM” it tells you what notes you are playing.
It also has a wheel of fifths, which tells you which key to play in and what position you’re playing in.
I hope this helps