SainSmart 20 x 4 LCD wanting to use I2C from Arduino Uno

How do I know which address to use as well? I have seen a lot of 0x27 stuff

Which LCD do you have?
What does the datasheet say?

5k is a good value for the pullups.

.i read how someone wrote you have to also code wire.begin but that just shows an error.

What does that mean, please?