The Benedictine Office becomes Roman for the next few days, so ignore all the parts of the Diurnal except what is set out at out at MD 265* ff. Note that there are no opening prayers, and the Gloria Patri is not said at the end of each psalm.
If you attend the evening Mass, you don't need to say Vespers, as it is included in the ceremonies. Compline is said according to the rubrics at MD 305* after the denudation of the altar, with extinguished candles and no chant.
Tenebrae of Good Friday (Matins and Lauds) is often said immediately after this.