First, welcome to LO - you should find this much nicer in many ways
than MsFt.
Now, to attempt to answer your questions:
LO is fairly easy to understand ... when you open it,
say you wish to to read or compose a textual document - choose
text document.
To compose, or edit, a document then check each of the tabs to set
the document the way you would like it to be -
if a portion later should be in another format, you can change
it at that time.
Or you can just begin typing, clicking on the tabs as you go along.
If you wish to make a spreadsheat, choose that option then check the
tabs - or not - and begin filling in the blanks.
As for the presentation option - I've quit using ppt for videos ...
these are more reliable & transferable between macines
ditto with the drawing option.
Hoping this helps,