creatinglightly

See some related infos about blending modes:
Blend modes explained (...Remember that blending affects all underlying layers not just the layer immediately below the blend layer) Your Big Friendly Guide to Layer Blend Modes Layer blending (help) Layer blend ranges *** (help)

You have to use an absolute size, not a size scaling. So for example if you want to export a particular slice with a width of 400px you have to input 400w.
If you want to add more sizes to that particular slice click on the plus marked on screenshot and add another one. You can also define a height instead of the width. In that case just enter 400h.
See the example on the screenshot - it will export slice1 in three sizes (widths): 200px, 300px and 400px.
 

Hi! One easy way I found to do this is:

1) Use the crop tool to crop the area you want (just as in Photoshop), then press enter.
2) Right click in the resulting layer, and click Rasterize...
3) Use the crop tool again to enlarge the area. That will fill it with a transparency.
Hope it helps!

Thanks! Yeah, that's the one I followed originally, but I must have messed up somewhere 
Thank you all for the replies! I consider it a good welcome to the forums. I'll stick around. Have a great week y'all!

That's certainly the workflow I'd use, to find out more about refining selections check out our following video!
 

It isn’t about the opacity of the selected pixels, it’s about the degree of selectedness. In the screenshot below, I set one square to 70% opacity and the other to 30% opacity. I then made a rectangular selection which I feathered by 80px: as you can see, the marching ants overlap both shapes but do not form a rectangle.
In the next screenshot you can see the effect of copying and pasting the selected region.
The 70% opacity and 30% opacity regions are both enclosed by the selection marquee, but the extremes of the feathering (less than 50% selected) are outside the marquee.

Hi creatinglightly
For the selection you're making I'd recommend using the Selection Brush Tool as using flood/wand selections will select like-pixels by colour, rather than edge detection. It looks as though the colours in the arm are close to some of the tones in the pebbles and this is my you're selection has 'mist' around it.
Try deselecting and using the Selection Brush Tool, as this will use edge detection to select the arm only

Well I tried it from a copy I made of your picture and it worked as expected.
Can you post the picture without the outline selected then I can show you what I mean.

I cannot explain why, but have you tried inverting the pixel selection, then just deleting the now-selected background?
John

Hi! One easy way I found to do this is:

1) Use the crop tool to crop the area you want (just as in Photoshop), then press enter.
2) Right click in the resulting layer, and click Rasterize...
3) Use the crop tool again to enlarge the area. That will fill it with a transparency.
Hope it helps!