Assuming you don't qualify for another IEC...
If you want to remain in Canada longer as a temporary worker, your employer will need to obtain an approved LMIA (permission to hire you) and then you'll need to apply for a close work permit tied to that specific employer. This is a fairly long and expensive process. Your employer should start six months before your IEC visa is due to expire. The first step is to advertise the role for at least a month to prove no Canadian could be hired. The next step is to submit the LMIA application for review and hopefully approval.
If you want to stay permanently, you'll need to educate yourself on Canada's various immigration streams and what it takes to qualify. You can find this detailed info here: http://www.cic.gc.ca/english/immigrate/apply.asp
