Hi,
There are any possibility to permit for someone to do registration for 3 events for example and use only 1 form to enter his information.
I have 10 events in the same day and I want that someone can choose 3 of them without complete the form 3 time for each event.
I think that's going to depend on how complex your registration needs are for each individual event - but based on what you say so far, you can set up one registration 'event' including a field that has a custom 'Checkbox' field - with the checkboxes representing your individual sessions.... People can then choose what they want and you can limit class sizes or whatever using the options available when creating this 'Checkbox' field.
Extending that you should (I think) also be able to create conditional custom fields that show only if certain check-boxes are picked....