In English, some verbs are followed by the infinitive with "to" (the full infinitive)
- want - "I want to go", "I want you to stay"
- promise - "He promised to do it"
- and there is a long list of such verbs (forget, agree, manage, decide, love, hate, watch, bid, etc)
Some verbs are followed by the infinitive without "to" (the bare infinitive)
- let - "let me help you"
- make (except in the passive voice) - "she made me do it"
- dare - "I dare not wake him", "I don't dare (to) wake him"
- need (except when conjugated with do/will/would) "You need not say anything about it"
- etc, etc.
Other verbs can be followed by infinitive with or without "to"
- help - "John helped me (to) push the car"
In your example, "want" is one of those verbs that can be followed by object + infinitive, just like tell, order, allow, encourage, request, forbid, warn, teach, etc) and in this case the infinitive has to be preceded by "to" (the full infinitive) This is just a summary. For more on the subject, CDO and Edufind and the OPG