well, they're part of the new brushes I downloaded
but I basically started out with a 500x250 window size (the maximum) then I put in the picture.
After that I put in the picture again, but with a little bigger size and cut-off in the background.
Then I made a new layer ontop and filled it with black.
After that I selected the Rounded Rectangle Tool and made a shape, but not over the whole sig, just enough room on the sides and a little above.
Then right-click in the Rounded Shape with the pen-tool, create selection and press delete.
now you can start making your siggy but keep the black layer ontop, so you can see how the sig will eventually look.
when you're done use the eraser tool, pick out a good-looking brush (I used the new ones, used 2 brushes on each side) and press just once, don't use brushes where you need to move around, only use 1-click brushes...
after that if it needs a little bit of fixing just use the brush tool (color black) to fix it.
when you're done ctrl+click the black layer, then press ctrl+shift+i , select a layer under the black layer and hide the black layer (if needed then you can also hide the (white) background layer, then go to Edit > Copy Merged.
now open a new window, if it went right you should see the dimensions of your sig when choosing the new window size, but make the dimension a tiny bit bigger, and then press ctrl+v, unview the background and save it as png
but I'm guessing you already know this Misuzu xD