It's pretty simple actually if you've used any sort of drawing software before!
1. Create a canvas in your chosen illustration software (Photoshop, Procreate, CSP, FireAlpaca etc.) which is the size of your monitor/laptop screen. (Standard is 1920x1080px WxH but it can vary). Fill in the background with whatever colour you like!
2. Some drawing softwares have a 'Tile Symmetry' function, where you can place items in one square and it will repeat in other squares on the page. This is pretty useful for making patterns but isn't completely necessary so don't worry if your chosen software doesn't have it.
3. Look up the items you want to use on the stardew wiki and they will have a png file of the item which is either the original pixel size or an upscaled version.
4. If it's the original pixel size, to upscale it just use the Transform tool you have in the software you're using (they will all have one!), and make sure the transform type is set to 'Nearest Neighbour' (Usually the default is 'Bilinear (smooth)' or 'Bilinear (sharp)' for whichever software you use, if that helps you to find it!). This mode is useful for upscaling pixel art as it keeps the straight edges. Make it the size you need, however if it's already upscaled to a good size then you don't need to worry about all that!
5. Arrange the items how you see fit, some drawing software have snapping tools so you can easily line up the items. I use FireAlpaca, and if you use the Move tool while holding shift, it will move elements along a straight vertical or horizontal line, very useful! If your software doesn't have that though, you can draw straight lines and then line the items up along it on a different layer.
6. Save the file as a 'png' type, this is a fairly lossless file type meaning it will keep your image looking crisp :)
Hope this was useful!
