As the world unfolds before you, remember to stop and smell the sweet petals of the flowers before you, and not run too eagerly to your goal!
As Seer said, start with the beginning. Many of the basic parts of magic, especially meditation, visualization and enegry flow and control, do not require you having tools, being loud, or being obvious about your practices. All of these you have probably done at one point or another without thinking about it. I would research into them, and see how they can be used while you are in the broom closet so to say.
If you have any questions, many of we on the site are always willing to answer.
No spell is going to work until you learn how magick works. I would suggest some education; basics consisting of meditation, energy, grounding, centering. Also Basics Extended in the forums is a good read, as well as Newbie Central. Blessed Be...
Begin with your basics (energy flow and control, meditation, and visualization) and become proficient in them, and spells such as the lost lover will work fine for you if you want to use them. :)
As for the replacements, replacing any ingredients is fine, just research into that particular ingredient and similar ones as well before making any changes or using them. Some of the spells on this website could do with better ingredients or different ones.