Congratulations on your new Octatrack MkII!
I recommend that you download the full manual for the OT MkII from Elektron’s website. As well as reference descriptions of the OT’s functions, the manual also contains a step-by-step tutorial on sampling.
You should also make use of the materials already available on this forum, by using the search function for terms like “Octatrack sampling tutorial” or “Octatrack MIDI sequencing tutorial”. There are a lot of tips for beginners and experts. If you’re stuck with anything, don’t be afraid to ask specific questions here.