How to set tabs in work document

[Robert111]

Hello,

In my mid 80's now, so please bear with me a bit.
Two questions, please:

a. Could someone please walk me thru the steps, very
specifically, on how to set a few tabs for a new document ?

Is the 'best' way via the Ruler, or... ?

b. I have an old document that whenever I put the cursor in the middle of the text line, it does not
go to any default tab, but goes to the middle of the next line.

Any thoughts on whaha this is ?

Thanks,

Bob