I am helping Howard Beard, a local historian with a subset of his collection of 15000 local old photographs. We use PowerPoint 2007, & even a few macros.

For websites I would advise screen dumps as JPG and incorporate them. Use Alt PrtSc on the webpage, open Paint or Photoshop (etc) and paste, and save. Then insert into a PP page.

Text overlays are relatively simple. They can be moved around.

Save PP as a presentation.

I would advise sticking to one application, PP if you have it. Libre Office I would trust but don't try to learn both systems.

The PP presentation can be advanced with a forward or backward keypress, but forward can be done with the space bar - play with it.

You can (I do) do a lot of fancy timings and soundtrack/talk tied to each slide, but in our case we convert to a movie for archiving with museums and "Gloucestershire Archives". For that I use the public library which is licenced for the latest iteration of Office, and PP therein can do the conversion, 2007 can't, though there are website. that will convert for you.

Best of luck, if stuck PM me from here or from mister.red , I may be able to answer questions that can be described textually.