Notating different length notes together

This is my first post so go easy! haha.
I've composed a classical guitar piece that I'd like to notate, and a friend suggested Musescore. I love that it is open source software, so thank you kindly to all the contributors. It's wonderful to discover this software.

The start of my piece is a chord of 3 notes, all played together. The piece is in the key of D, and the 1st chord is a D chord.
The D is played on the 5th string of the guitar (5th fret), F# on the 4th string and A on the 3rd string. The D and the F# are held for a half note and the A is held just for the eighth note. I know what this is supposed to look like, but I can only seem to have all 3 notes the same type. I'm picturing the notes in the same vertical line, but is this not correct? How to do this in the software is what I'm looking to answer.

TIA
Michael