You always capitalize the first letter of a sentence, and you always capitalize things called "Proper Nouns". Nouns in general are just words that refer to objects, like desk, leg, seal, ice. Proper Nouns are words that refer to specific places or people. Like you always Capitalize peoples names, and if you're talking about Mt. Everest you would capitalize it like I just did. If you're doing titles, people usually capitalize every word except words like of, if, and, from, etc... I'm sorry I can't be more definitive on the titles section.
