„Dla mnie” can work, but above is good, too. Usually it will be clear in context.
„Wysłać” is what one might call a generic perfective aspect of „słać”. You can also have other perfective verbs created from „słać”. If by "sent out" you mean sending massively to many recipients, then „rozesłać” is the word.
In case of messages, in Polish „posłać” and „wysłać” are synonyms. There are specific situations where they are really distinct:
If you send a signal, radio for example, you do it with „wysłać”.
If you "send" something by shooting/throwing/kicking (like an arrow to the target) you use „posłać”.
The similarities are interesting. Poslat' means to send something, in the perfective aspect, but not necessarily with any urgency. Wyslat' means to send out from somewhere, to "get it out of here/there," implying a sense of urgency at least in the item's leaving the place of origin if not in its arrival at the destination.
the message tells me I am writing in english. Unfortunately I don't have the Polish alphabet on my ipad , but for some stupid reason when I use my laptop the extra Polish letters appear on the screen when doing an exercise. Means I have to get out of my bed and walk downstairs .Duolingo will have to wait
An even better idea is to download a Polish keyboard for your iPad.
I don't have any idea how it works on iOS specifically, but on Android you can find such option somewhere in the system settings or keyboard app settings. Then you are able to switch between the two.
In order to type a Polish letter, you hold your finger on the base letter. The tiny window will then pop up, giving you a choice of special letters.
Then it was most likely the accusative or genitive 'mnie'. I don't believe we teach the emphatic dative 'mnie' in this course at all.
There are examples when dative 'mnie' can be at the end, but they are rare: 'Nie jest to potrzebne ani tobie ani mnie.'
Btw, the post-prepositional form of 'mi' is also 'mnie', same as the emphatic form.