Hi guys, i'm doing a AC simulation to see the open loop gain and phase of my OTA. It has not symmetrical supply (1.8 V and 0 V). I can't figure out which voltage (AC and DC) i should put in Vin and Vip.

Open loop AC measurements aren't done with the circuit in actual open loop. You should use a testbench like this one, with very large capacitor and inductor in the feedback. And the AC value should 1, not 1.8. https://www.edn.com/designing-with-a-complete-simulation-test-bench-for-op-amps-part-2-small-signal-bandwidth/

And the DC values? Because my ota has a not symmetrycal supply.

The DC values are ok, but it all depends on your application. If it uses some kind of feedback, it is not a problem.