This works for a csv with 100-200 products. It won’t work for more products because your server will not allow such a load on the server (when you import the CSV).
Go to Admin > advanced parameters > import CSV.
If you want to import products, select “products”.
Upload the CSV file.
Select the language.
At ISO, select no.
At “separator”, select | or ;, depending how your CSV is structured.
Your products are separated usually by “,” and the values from a product as “|”. Values like “name of the product” | “image” | “price” and so on.
You can choose to delete the exising products if you like.
Second option, leave it to no.
Skip thumbnail, select yes.
Force all id numbers, select yes.
Atribute stuff depending on your csv. If you see weird values, select ignore this column. Import the csv.