In a situation like this, installment credit would probably be the best option for you.
Installment credit allows you to purchase an item, and then pay for it in installments. The reason that this would be the best option for you is that you do not have the money now to make the purchase, but you are able to make small monthly payments for a computer.
Installment credit is better than revolving credit for new borrowers. Revolving credit would allow you to charge more purchases on your revolving credit account. The installment pla only finances one item, rather than a credit card which is how revolving credit works. You would not choose non-installment credit because this would require you to make this payment all at once in a short period of time. It would not allow you to spread the payments out over time.