Give the soil a good soaking and then dig the weedy grass - which perhaps is not the same kind that makes up the lawn - and spring bulbs out with a fork, being careful to get the bulbs and their own roots in the process. Dispose of the grass and re-plant the bulbs in another spot - if you want to keep them. Of course you will have to be careful around the rose and the lily(?) in the back corner.

Once you take the time to get all the grass roots you can see then you should be able to go to garden centers and find plants you like, plant those in your now cleaned bed. Sprouting from pieces you missed can be dealt with during subsequent inspections - the key to staying in control is to return often enough.

some ideas:

dg out the grass or use Roundup, plant, fertilize & mulch, apply Preen to prevent weed seed germination

I have a triangle garden in front of my entry door. I have tulips, crocus, stella doro daylily, and coreopsis. The daylily is around the outside of the triangle with the coreopis in the middle. When the tulips and crocus are done blooming the daylily and coreopsis fills in and hides the fading tulips. Wait till after a rain and dig out the grass. It is easier when the soil is moist.

That's a small area, you want to plant it up, rather than use landscape fabric. Landscape fabric is used under mulch and the sides of your garden aren't high enough to keep the mulch from spilling over onto the driveway, leaving ugly, bare fabric on your garden.

It's not a lot to weed and dense planting will keep the worst of the weeds at bay. Roses don't like crowding, so I'd keep the plants to low-growing ones. Coreopsis works, as does creeping phlox and geranium maculatum. It's also small enough that you can plant annuals there. They tend to bloom all summer long.

Roses also don't like glyphosate (RoundUP etc.) and as far as crowding goes they simply grow up taller and through other shrubs or trees that are near them. But the rose would still be left to be the dominant visual element in this scheme simply because the bed is so small. For continuity of all involved elements plants used should taper up and down in height with the width of the bed, so that having the rose in the widest part of the bed - as it is now - is perfect. Doug's cartoon with a bird bath and variegated yucca in the narrowest part of the bed produces instead a visual conflict between the shape of the bed and the size of these elements. (And the rose does not appear to have been considered at all).