creating new file in photoshop
Opening an image or other documents in photoshop is quite easy, just right click on the file and select open with Photoshop and it's done or open the Photoshop application and select Open from the File menu and browse through the files to find the right one and select Open. But, if you are going to create a new file you need to know a few things.
Go to the File menu and select New. You can use the shortcut key Ctrl + N as well in order to create a new file. After you make the selection, a new document setup dialog box will appear which will look as shown below.
You can provide a name to your file from here or you can opt to give it a name later while saving the final document too. In that case, the file be named as Untitled-1 as default.
Photoshop contains multiple page sizes that are used regularly. You can select anyone of them as per your need or choose custom to define custom width and height for your document.
This option is available for some of the presets that contains multiple size options. You can select one of the sizes for your document from here.
Width & Height
You can further customize the height and width of the document from these options or define some in case of custom size. The values need to be inserted in the left input fields while multiple standard measurement values are selectable on the right.
Resolution is the number of pixels on a printed area of an image. Higher resolution means higher quality as well as bigger file. The standard resolution for documents to be printed is between 150-300 and 72 for Web documents.
RGB is the standard color mode for web documents while CMYK is the standard color mode for the documents that are required to be printed.
Select the background as per your requirement from the last input field where the available options are white, color or transparent.
If you are creating a custom size that you may need in the future again, you can select the Save Presets option to save it and it will appear in the preset option afterwards or just click OK to create a new file.