[Azaghal]

Hi, Tyranny]SiN[!
I'm an absolute beginner with Morrowind, but maybe I can help with the bow and spellscrolls. Don't blame me if I'm wrong. Wait patiently for someone with more experience.
Draw both the bow and the arrows over your avatar in the inventory. They should be displayed surrounded by a white box after that. Then swith back to the game, press "F" and your character will draw the active weapon (should be bow by now). Hold down your left mouse button and you'll automatically put an arrow on the string and get ready to shoot. Aim (to my total shame I admit I still use the target cross) and release mouse button. The arrow will fly.

To use a spellscroll rightclick to open your inventory. Select the scroll you want to use in your magic menu (lower right side at least on my screen) and a symbol for the spell selected will appear on the main game screen next to the little symbol that represents your active weapon. Now press "R" to go to spell casting modus, leftclick and the spell will be casted. Don't forget to aim first if it's a target spell.

Hope I didn't get your questions wrong because I am absolutely flattened that you are on level 18 without bows and spells. Good luck!