The continuous tense both present and past are formed in Portuguese by using the appropriate form of estar verb together with the participle form of the verb of action.

The three regular form of verbs have the following conjugations in present and past participle form.

"eu estou falando" - I am speaking.
"eu estava falando" - I was speaking.
"Tenho falado" - I have spoken..
"Tinha falado" - I had spoken.
For more verbdetails the link is given below. You can go to the website and learn more about Portuguese verbs.
http://www.verba.org/verbi/all_verbs_index-pt.html