I would like to install Manjaro alongside Windows 7. I think I will need to choose “manual installation” in Manjaro’s installer. But I’m not sure of setting up the partitions for Manjaro like boot, swap etc and what sizes they should be.
The free non-allocated space can be used for Manjaro then.
You need at least 1 partition for root /, but I would recommend creating a second efi partition just for manjaro to reduce the risk that windows could eventually wipe the partition and therefore make Manjaro non-bootable.
Swap can resist on the same partition as swapfile and since it is a SSD, a swap partition makes no sense here (for example putting the swap partition at very first, to speed up swapping on HDDs).
A boot partition is not necessary. The EFI partition would be there for booting.
Hope that helps for the beginning
Note: It is not clear, if you installed windows in BIOS or EFI mode. Keep sure both OS are installed in the same mode, so that grub finds windows.