Go to Inventory -> All and on the rightmost side, near the Create Product button, you will see two white buttons. Import and Export.
Before Importing Inventory you first need to download an example .csv file, so that you would know how the table should look. There are two options to do that.
First, You can get the most up-to-date .csv format by simply exporting inventory items. To do that, simply press on the Export button, and then Export All.
Note: downloaded files will be found in the Reports section.
Second, by clicking Import and pressing Download Example tsv. or csv. Import Sheet
Open the now downloaded sheet and fill in the fields as per the example (try to fill in as many fields as possible). After you're done, simply press Save and go back to Multiorders Inventory page.
In here, press Import and then press Create, then Choose Sheet find the .csv file you have just saved and press Import.
Depending on the volume of inventory this could take a few seconds or a few minutes. If however the upload has completed and the new inventory did not appear, there may be a problem in the way you filled out the .csv sheet.
Contact customer service in this case and they will be able to fix your sheet.