How can I make schematic of this board?
My personal favorite way is to take a photo of the board from directly overhead, flip the board over, and photo the bottom.  Keep the camera exactly the same distance away (a mount helps.) Then take these images, with software like PhotoShop or GIMP, and flip the bottom image horizontally, and stack these on top of each other as layers.  Then you can play with transparency to &quot;see&quot; both sides of the board at the same time.
Then you can see what pins of what components connect to what. I'd make another layer, and sketch the symbols of what the components actually are. Then add &quot;wires&quot; following the bottom traces to result in a &quot;schematic.&quot;
Once that is done, hide the photos and look at just the schematic.  It will be valid, but drawn horribly. From there, I would enter this into a schematic capture program such as KiCAD.  Then rearrange things to make it understandable and to follow schematic convention (from doe.gov).
Note that there is a lot more to schematic convention than this one linked document. It is also slightly wrong in my opinion, or at least old-hat, as I was taught that transistor arrows should always point downwards or right. Grounds should always point down. Inputs always on the left, outputs on right.
Edit: Once you have an image like @Mattman944 demonstrates, start sketching on a new layer like the following:

Once done, redraw it to look possibly similar to this (courtesy Power Integrations):