How can I predict new data in R after regress model?

Question

I want to plot and generate new data based on my Regression Model which I created:

Trend <- seq(1:length(Daten$TSLAC))

TISPYNVDA_TSLA <- lm(TSLAC ~ Trend + SPYC * NVDAC, data = Daten)

summary(TISPYNVDA_TSLA)

plot(predict(TISPYNVDA_TSLA), type = "l", 
     xlab="geschätzte Werte der abh. Variablen", 
     ylab="geschätzte Residuen", main="Residuenplot", pch=20)

lines(Daten$TSLAC, col="red")

As seen above, I created a trend sequence for the creation of future data with:

newline <- data.frame(wt=predict(TISPYNVDA_TSLA))

The function:

TISPYNVDA_TSLA <- lm(TSLAC ~ Trend + SPYC * NVDAC, data = Daten)

creates the regression. After that, I plot the regression together with the real data on TSLAC (Tesla Close Price).

Then I want to predict further afterwards as a "future prediction".

How can I do that?

I tried the predict() function, but it's not working:

lines(252:350,predict(newline,newdata=newline))

252 because the data is going to 251, then it should predict in the future.