Help with summing totals using multiple texts

Thank you both for taking the time to respond.

It won't let me attach a copy of the spreadsheet but here is a link to it

https://1drv.ms/x/c/c35c074091694af2/IQD6efwQOYdiQKOITnxt4AyqAYWnf9GmFLCdyknPrHOBB4Y?e=sbX5Pv

 
I am a novice with excel so I have developed the spreadsheet the best I can with my current knowledge.
I didn't know how to set it up for if someone orders multiple of the same item so when that has happened I have just been entering it on the row below. If there is a better way then I am open to all suggestions.

The blue section was just an extract of the spreadsheet I have for the logo sizes (it has its own tab in the worksheet) but essentially if someone was to order a 'YOUTH M (7/8yr) Hoodie' then that requires a 6cm AND an 18cm logo (one for the front of the hoodie and one for the back). However a 'YOUTH M (7/8yr) T-shirt' only requires a 6cm logo for the front as it is not having a logo on the back.

The text for all the entries should be the same as I have created the spreadsheet with drop down lists so that I can just select the relevant items on each order. What is data validation?

I will have a look at possibly re-doing the spreadsheet, I just wanted something that clearly displayed what each person had ordered so it could be referred to when packaging orders. 

Thank you for your help