While French has the same alphabet as English, some of the letters have little decorations that can make them look and sound very different. In French, accents are essential: they're there for a reason, so you must include them when writing.
In French, E is the only letter that can be modified with l'accent aigu, the acute accent. With the accent, it may be called either e accent aigu or simply é, pronounced [e]. As indicated by the latter, the acute accent changes the vowel's pronunciation to [e].
The little hook added under the letter c in French is a diacritical mark known as a cedilla, une cédille: ç. The letter c with the hook is called c cédille.
The dieresis, le tréma, is a French accent found only on three vowels: ë, ï, and ü. The dieresis usually indicates that the accented vowel must be pronounced distinctly from the vowel that precedes it.
Only three French vowels can take the grave accent: à, è, and ù, and the purpose of the accent depends on the letter in question.
Inversion with the first person singular je is a little trickier than with other subject pronouns. It's also very formal and therefore rare, so one of those grammar concepts you need to recognize but not necessarily use.
When the letters o and e are pronounced as a single sound, they combine into a symbol called a ligature: œ. The pronunciation of this symbol depends on the letter(s) that follow it.