Cutting:
Seam allowances are included - 1cm wide or as per marking clips!
When cutting, transfer all the notches you've drawn onto the fabric – these are the small lines running perpendicular to the cutting line. Either make a small mark with a self-erasing marker or a
Make a 3 mm slit with scissors. Cut the pattern pieces out of fabric, always clipping the seam allowance along the fold, as this is always the center.

To sew your shirt, you can use an overlock machine and a home sewing machine, or just your home sewing machine. If you don't have an overlock machine, use a zigzag stitch to neaten the fabric edges to prevent fraying. The colored lines in the images, in addition to the description, show you where to sew or glue something.
I hope you have fun sewing!
First, iron the overcasting strip wrong sides together (into the fold) and cut the tip in the center back to form the slit.
Sew the overcasting strip to the slit.
Fold everything inwards and stitch the strip 3mm from the edge.
Finally, sew the tip of the slit together to form a small corner.
Sew the front sleeves to the front piece and neaten the seam allowances together.
Take the lower back piece and gather the seam towards the sleeve.
In the front piece, you have two darts under the bust that need to be gathered. To do this, first sew a large stitch along the bottom of the dart. You'll need this seam to gather the dart. (We normally sew two lines for gathering, but here, due to the short distance, we only sew one.)
Once you've done that, cut the dart just before the point. Now gather the bottom part until it matches the top part...
… and sew both together.
Then neaten the seam allowance and iron it upwards.
Now you need the lower back piece and the sleeves. Sew them together...
… and again neaten the seam allowance and iron it upwards. 
Iron the seam allowance away from the tip and stitch it flat. 

Now iron the strip inwards and then sew the button loop onto the left side of the slit.
Place the side and sleeve seams right sides together and sew them together. Neaten the seam allowances together.
Now neaten the sleeve and shirt hems and iron the hems inwards at 2cm and topstitch everything.