How do I do find selection options

Hi John,

Whenever I want to add a few pixels to my selection in Photoshop...

I go to Select > Modify > Expand (to increase)

Then I choose the number of pixels I want to increase it by in the Expand Selection dialog box

Note... choose Contract to decrease the number of pixels.

like when you've selected round an object with pen tool, you could make a selection but increase the curviness of the selection or you could bring the selection in a bit by a certain amount of pixels?

That sounds like path. In Window > Paths, click to select the desired path. Once the path is visible, you can use the Direct Selection tool (white arrow) in Joe's screen shot above to adjust the anchor points, the control handles or the path itself. When you have  completed adjusting the path, you can click the Convert Path to a Selection button at the bottom of the Paths panel to convert the path to a selection.

New in CC 2018, once you select a path, you can click the gear button on the options bar to set the color and thickness. This doesn't change how paths work compared to earlier versions, but it does make them easier to see.

Are you working on a selection (marching ants) or a Pen Tool Path?

For a selection:  You can Transform a selection via Select > Transform Selection, or use the Select > Modify tools.

For a Path: You use the Path Selection Tool or Direct Selection Tools.

Good Luck!