Note that these answers apply to version 1.0 only!

Things you might be puzzled about:

How do I save/export my diagram?

Sorry, you can't. The easiest way to export your diagram into an image, is to take a screenshot and then crop it in an image editing software.

Chemix has a weird interface

Yes, it probably doesn't follow any established interface design rules, but this shouldn't make it hard to use. Refer to the instructions

I find it hard to drag things

This is most probably because you stacked too many things on top of each other. This is a bad idea anyway, your diagrams are supposed to be clear.

How can I select multiple items at once?

Sorry, you can't, such feature is not implemented yet.

How do I pan my workspace?

Sorry, you can't either.

How can I erase my diagram?

Either restart the application or drag the bin (by clicking on the bar above it) over your items.