"To"

I have a Spanish friend who has asked me to explain how we use "to" in English as he finds it very confusing. At first I thought it was as simple as a direct translation. For example...............
Spanish: Quiero verlo
English: I want "to" see it
Spanish: Necesito hacerlo
English: I need to do it
Nice logical pattern............... but with some verbs the rule does not work
Spanish: Puedo hacerlo
English: Literal is; "can I to do it" but we say "Can I do it" (Where is the "to"????)
Is this just a simple case of irregular verbs or is it more complicated? If someone can explain it would be appreciated.

[Casiopea]

Welcome.

Some verbs take an infinitive verb (to + VERB) as an object. Examples,

want [to go]
need [to have]
have [to see]
like [to eat]
supposed [to do]

Can is not one of those verbs.

All the best.

[fryerka]

I have found out some futher information with regard to my question on "To". Basically I think I am talking about "Modal Verbs", for example Will, Shall, May or Might, Would, Can or Could, must, should and ought. None of these verbs are followed by "to" (note, Ought is an exception "ought to" but is still a modal verb).

[Humble]

Hi,
another verb - make.