If it is your first time to apply for a study permit ..
You have following categories in which you can apply :
1. SPP
2. UNIVERSITY CATEGORY
3. GENERAL CATEGORY
1.
As you said , your parents didn't have enough money to support and you are borrowing from your uncle . So , you should go with SPP category .
You need to pay atleast 1 sem fee ( 6000-8000 cad ) , gic ( 10000 cad ) and your parents income tax return . You don't actually need to attach the ITR but you have to mention in the from ho wmuch they pay for tax . CIC can ask any time for additional document like itt if they want .
You don't need to attach any loan document , any sponsor or support letter , any evaluation in this category . It is common among most of the international students who want to study in a designated SPP college recognied by CIC.
2. For uni. catgory , fee is much higher than colleges and i don't think your financial conditions allow you to go with this category . Actually , it is the best but the fee is higher . If your uncle can afford ( 20000-25000 cad / year for fee ) + you need to show $10000 for living expenses in form of fd/loan/bank statments / sponsors + funds for ticket + itr .
Then you are good to go with this category .
Note :- Uni. are far more better than colleges and can provide a better platform for you to settle as you are a 18 year old and have no experiance .
3. Don't think about thios category unless you are rejected from any one from above.
You are a new student who has no idea what to do and how to do . Thats why i explained you that much briefly . Long time back , i was at your age . I put same questions to many people but no one answered me accurately .