When you installed Firefox you should have been given the opportunity to import your bookmarks from Internet Explorer. ('Bookmarks' are what Firefox, and everyone else, calls what Microsoft refers to as 'favorites' - with that horrid US spelling).
If you did so, once you've opened Firefox you can now access your bookmarks via the Bookmarks menu at the top of your screen. (Alongside 'File', 'Edit', etc).
(Note 1: If you didn't import your bookmarks from Internet Explorer when you installed Firefox, you can still do so:
https://support.mozilla.org/en-US/kb/import-bookmarks-internet-explorer )
(Note 2: You can add new bookmarks at any time by going to the relevant page and then clicking on Bookmarks > Bookmark This Page, or by simply pressing Ctrl and D together).
(Note 3: If you've not got 'File', 'Edit', etc across the top of your screen, right-click at the top of your screen and click to put put a tick next to Menu Bar)
However it seems likely that what you're referring to as a 'favourite' is actually a desktop shortcut. (i.e.it appears on your desktop even when your browser is closed but allows you to open your browser with the required page already selected). If so, this explains how to create desktop shortcuts with Firefox:
https://support.mozilla.org/en-US/kb/create-desktop-shortcut-website
(Note 4: If you no longer require an Internet Explorer shortcut on your desktop you can simply right-click on it and select Delete).
With
all popular browsers (including both Internet Explorer and Firefox), you can increase the size of everything displayed by pressing Ctrl and + together. Pressing Ctrl and - makes it smaller. Pressing Ctrl and 0 takes it back to the default size.
You can have whatever home page you want with Firefox. Simply go the page you require and click on Tools > Options. (You can also use the button with three horizontal lines on it, at the top right of your screen, instead of Tools). The General tab will probably be preselected. If not, click on it. The click on 'Use Current Pages'.