Training is an essential part of any project involving SAP and how people should learn SAP, it’s not really an application you can expect users able to work it out as they go along. The sheer scale and enormity of what is possible with SAP dictates that a lot of functionality and options have to be packed into each and every screen, limiting the ability to make a truly intuitive experience.
At first this can seem like a negative and can put people off SAP from the start. But remember it is this scale and complexity that makes SAP experience valuable to employers.
Also from an employer’s point of view don’t see training your employees properly in SAP as a threat that they will then leave. Maybe they will maybe they won’t but if they’re properly trained they will be happier and will have the knowledge of how best SAP can work for your company. If they have a good knowledge of SAP they may be more likely to use the standard reports/functionality available and if they do leave at least you know that the system is set up and used correctly. This will make finding a replacement with SAP knowledge relevant to your system and who can hit the ground running much easier! If they are not trained, have little knowledge of SAP and its standard reports and transactions they are just going to set it up as best they can and could end up getting the ABAP team to write bespoke reports/program which may already exist as standard.
Your first port of call for training is going direct to SAP who offer a large range of courses in all areas. I would highly recommend these but they are not the cheapest, which means they are probably only a realistic option if you have a job in the given area and your company is wanting to send you on the course. See here for information on Training from SAP
An alternative option especially for SAP development and configuration is Video training material, I feel you would be a good option along side using information found on websites and ABAP development books. See here for ABAP/SAP Video training
SAP training books provide an excellent way of getting up to speed with your SAP knowledge at a relatively low cost, They are also very useful to refer back to at any time if you need to quickly jog your memory. See here for ABAP/SAP Books.