generating po mo translating files from scratch in a wordpress theme

Question

Maybe I'm missing something here but I really can't find any answer to my question around the web.

I am creating a new wordpress theme from scratch (literally from scratch) and would like to create languages folder with PO and MO file in it.

I would like to generate this translation MO file from scratch

I was looking for a good tutorial that will get me started and let me understand the whole procedure but all the good tutorials I found all talking about how to translate strings that are already exist.. meaning that a MO file exists already, the strings are already in it and I need to translate them.. that's pretty easy but that's not what I want.

I would like to generate something from scratch using my own custom strings.. + I want to always be able to add more strings and compile it again to update the PO file.

can anyone send a good tutorial of how o do it from scratch? am I missing something here?

Thanks a lot