I'm is the contraction of I am. For more about the pronoun I, the word am, contractions and the use of the apostrophe, follow the links
more information: am , is or are
Notice that here your is spelled without an apostrophe because it is a possessive adjective. Follow the links to find out more.
more information: your & you're
Follow the link to discover the three spellings and uses of the words pronounced the same way as whether.
more information: weather & whether