Export a csv file containing the grades you wish to put in Canvas.
From WeBWorK:
Click on "Scoring Tools".
Select the assignments whose grades you wish to export.
Uncheck all three checkboxes (from "Include Success Index" to "Pad Fields").
Click on "Score selected sets and save to".
Below "Totals", you'll see a link to a csv file. Save this file.
From Gradescope:
Click on "Assignments".
At the bottom of the page, click on "Download Grades". You may have to click on "More" first.
Save the csv file that Gradescope generates.
Use a spreadsheet editor such as LibreOffice or Excel to edit the grades themselves as necessary.
You may wish to rescale each item to be out of, say, 100 points. Click here for detailed instructions.
Canvas allows you to drop the lowest n scores; if you want to do anything more complicated, e.g., weighing the highest exam score more heavily than the lowest exam score, you will have to do this within the spreadsheet.
Reformat your csv file to be Canvas-friendly. Brief instructions are below; click here for detailed instructions.
Replace the "Last name" and "First name" fields with a single "Last, first" field. The formula =CONCATENATE(B4,", ",A4) will accomplish this. Be sure to "cut" the results and then "paste as text".
Insert two empty columns after the name column.
Insert an empty row after the header row.
Change the column headings of the first three columns to be "Student", "ID", and "Section", and write "Points Possible" in cell A2. Delete any columns other than these three and any columns containing scores themselves.Your spreadsheet should now look like the following:
Save your csv file.
From the Canvas Gradebook, click on "Import", then choose your csv file and follow the instructions.