Change the simple past tense to the simple present tense. For example, a simple past-tense sentence that reads "I smiled" can be changed to "I smile," which is simple present tense.
Change the past progressive version of the sentence to the present progressive. For example, changing "I was smiling" to "I am smiling" will change the past progressive tense to present progressive tense.
Change the past perfect tense to the present perfect tense. Instead of "I had smiled," write "I have smiled."
Change the past perfect progressive tense to the present perfect progressive tense. For example, change "I had been smiling" to "I have been smiling."