The grammar you are using is incorrect, but I think I know what you are trying to ask.

"I used to swim" means that the person has swum in the past.

"I am used to swimming" means that the person is familiar to swimming / practiced in swimming.

<ol><li>I swam / I was swimming. These could mean a couple things in the past, definite (I swam [was swimming] yesterday.) or continuous (I swam [was swimming] competitively all the way through highschool.). These are also the choice for the immediate past. While "was swimming" is more the choice with continuous past often used as a lead-in to a narrative (I was swimming regularly back then, just before I got into the university.), but otherwise they are used about the same.</li><li>I have swum / I have been swimming. These are undefined past tenses most often used to confirm generalities (Have you swum before? Yeah, I have been swimming before - I don't need any help.). They are also rarely used with specific time modifiers and rarely for the immediate past.</li><li>I used to swim / I used to go swimming. These are used like a mix of "I swam" as they usually take a modifier (I used to swim in the river with my friends.) and "I have swum" as it is rarely used in the immediate past (I used to go swimming every summer.). It is almost always used to demonstrate change (I used to swim for fun, but now I only swim laps! I used to swim, but I can't now because of my injury.).</li></ol>